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https://issues.apache.org/jira/browse/FLINK-1238?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14209598#comment-14209598
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Stephan Ewen commented on FLINK-1238:
-------------------------------------
There is a related issue with the object creation in GroupReduce:
By default, we create a new object for every element, but we also have a mode
to reuse objects (Hadoop style). That allows you to simply gather elements, but
it also puts more pressure on the garbage collector.
Should we expose both with the same switch?
> Add a way to deactivate the "mutable object safe mode"
> ------------------------------------------------------
>
> Key: FLINK-1238
> URL: https://issues.apache.org/jira/browse/FLINK-1238
> Project: Flink
> Issue Type: Improvement
> Components: Local Runtime
> Affects Versions: 0.8-incubating
> Reporter: Stephan Ewen
> Priority: Minor
> Fix For: 0.8-incubating
>
>
> Currently, the runtime operators for Join and Cross operate in a safe mode
> concerning objects:
> Whenever a cross or join function is called with the same object more than
> once (for cross always, for join in all but the 1:1 join cases), the runtime
> makes deep copies of the objects before calling the join function.
> Even if the join function modifies the objects that were given into the
> function, the next call to the function will pass the original unmodified
> value. It is a safe mode for programmers that operate more in a Hadoop-ish
> way, were it was very common to modify the objects rather than creating new
> ones.
> I would add an option to disable that mode, as it does cost performance.
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